Question: What is the least common multiple of 6 and 21? Another way to say this is: $\lcm(6, 21) = {?}$
The least common multiple is the smallest number that is a multiple of 6 and 21. We know that 6 x 21 (or 126) is a common multiple, but is it the least common multiple? Write out the multiples of 21 until we find a number divisible by 6. 21, 42, So, 42 is the least common multiple of 6 and 21.